Absorption refrigerating machine



May 21, 1935. E. ALTENKIRCH ABSORPTION REFRIGERATING MACHINE Filed Aug.14, 1930 2 Sheets-Sheet 1 Fig. I

. Era- May 21, 1935. E. ALTENKIRCH 2,001,697

k v ABSORPTION REFRIGERATING MACHINE F'ile d' Au 14, 1950 2 Sheets-Sheet2 Patented May 121, 1935 2,001,697 ABSORPTION asrarcsaa'rme moms EdmundAltenkirch, Neuenhagen, near Berlin, Germany, assignor, by mesneassignments, to The Hoover Company, North Canton, Ohio, a

corporation of Ohio Application August 14, 1930, Serial No. 475,206

In Germany August 20, 19 29 4 Claims. (01. 62-1195) My invention relatesto an absorption refrigerating machine with a working medium whichcondenses at atmospheric pressure at a tempera- 'ture of about 10 to 20degrees centigrade above the highest room temperature practicallyoccurring. This is, for example, the case with ethylene dichloride. Anabsorption refrigerating machine of this kind has a number of importantadvantages. The pressure at which the pure working medium condenses inan air-cooled condenser, even under unfavorable cooling condi tions isjust below the atmospheric pressure, whereas in the absorptionrefrigerating machines known up to the present the condensing pressurewas as a rule either considerably higher or considerably lower than theatmospheric pressure' With the subject-matter of the invention, bothdisadvantages, existing if the internal pressure of the machine is aboveatmospheric, for instance, the possibility of the working mediumescaping into the surrounding space, and the difficulties caused if ahigh vacuum is to be maintained, are eliminated.

Owing to the comparatively low pressure in the whole machine, thedifference in pressure between the evaporator and the liquefier is alsosmall. If water cooling is employed, the difference inv pressure cantherefore, be equalized by columns of liquid, in order to be able tooperate without pumps or valves. The liquid columns need in this caseonly be made moderately high, so that the machine is very suitable forhousehold purposes. If air cooling is employed, the height can bemaintained within the desired limits by admixing a neutral gas.

Among the organic substances possessing the property mentioned at thebeginning, the said ethylene dichloride is, according to the invention,employed to great advantage as a working medium. Its condensationpoint'is (at atmospheric pressure) at +55 degrees centigrade, itssolidifying point lower than -70 degrees centigrade i. e. lower than thenecessary evaporating temperature practically required for mostpurposes.

As a solvent for ethylene dichloride, according to the furtherinvention, paraflin oil is to be employed. Paraflin oil has a very highboiling point, about 360 to 390 degrees centigrade. This fact makes itpossible to raise the temperature for heating the expeller to aconsiderably higher degree than is possible for example with aqueousammonia solutions even at high pressures. Now, large differences betweenthe expelling temperature and the condensation temperature meancorresponding low temperatures in the production of cold. Moreover, whenethylene dichloride is being expelled from a solution in paraffin oil,an evaporation of considerable quantities of the solvent need not bereckoned with.

' The specific gravity of paramn oil is lower than that of ethylenedichloride, and this fact influences favorably an automatic circulationof i the liquid between the generator and the. absorber, disposed at ahigher level.

If cold is not produced by evaporating the condensate but by expellinggas from a strong absorption solution of ethylene dichloride in parafiinoil, the mentioned working medium is also suitable for absorptionrefrigerating machines op-' erating with air cooling and without anindifferent gas. The diiierences in pressure can in this case also bemaintained by means of columns of liquid of a small height.

If water cooling is preferred, then one obtains,-

for operation with ethylene dichloride, a very simple construction ofthe absorption machine, since the admixture of indifierent auxiliary gasis in that case not necessary. Thermically, the manner in which amachine of that kind operates is so favorable, that it is suitable forbeing built for very large refrigeration outputs. v

In the drawings, the invention is diagrammatically illustrated in twomodifications.

Figure 1 shows a continuously acting absorption refrigerating machineoperating with condensation, in which an indifferent auxiliary gas (air)is mixed with the gaseous working medium (ethylene dichloride) in theevaporator and absorber, whereas Figure 2 illustrates an absorptionrefrigerating machine operating on the re-absorption principle andwithoutan auxiliary gas.

In the arrangement according to Fig. 1, liquid ethylene dichloride flowsfrom an air cooled condenser I5 through a pipe 2 into the evaporator I.

By falling in drops over the baffle plates 3 in the evaporator, itevaporates into the mixture of air and ethylene dichloride, which isweak as to its co'ntent of working medium, and which passes through theevaporator from the bottom to .the top. The gas mixture streaming intothe bottom of the evaporator I through the pipe 4, leaves theevaporator, after having enriched itself with ethylene dichloride, atthe top through the pipe 5, and then passes through the pipe 6 into thebottom of the air cooled absorber 1, provided with ribs i8. 'Inside theabsorber, weak absorption solution, conveyed into same through the pipe8 andconsisting of parafiin oil and ethylene dichloride, falls in dropsover the bailie plates l9 fittedin the absorber; it gathers at thebottom and flows off again through the pipe 9. The pipes 8 and 9 are soarranged as to exchange heat with each other. In the absorber, thesolution absorbs a great part of the working medium from the gasmixture, so that the latter only retains a small content of ethylenedichloride, when it leaves the absorber through the pipe 4. The enrichedsolution flows from the absorber through the pipe 9 into the generatorI!) which is heated ride gas is conveyed through the pipe l4 into thecondenser l5. Here it is condensed, the heat of condensation being givenup to the surrounding air. From the pipe I, a pipe l6 branches off,which ends in a nozzle l1 arranged in pipe 6 conveying gas mixture. Theethylene dichloride gas discharged through this nozzle imparts a motionto the gas mixture, causing it to move in an upward direction throughthe absorber and the evaporator. The circulation of the gas mixturethrough .the evaporator and the absorber takes place in the directionindicated by arrows, i. e. in the contrary direction to the flow of theliquids.

In the arrangement according to Fig. 2, gaseous ethylene dichloride isdeveloped in the generator 2|, heated by an electric heating element 22,from a solution of ethylene dichloride in paraffin oil. The gas expelledthrough the supply of heat rises, in mixture with the absorptionsolution, in the upwardly extending pipe 26 up into the gas separationchamber 2|, the absorption liquid separate. Whilst the liquid passesthrough the U-shaped pipe 25 into the air-cooled absorber 26, the gas isconveyed through a pipe 28, opening into a rising pipe 33, filled withsolution, to a re-absorber 29, also air cooled, which is connected, bymeans of a pipe 36, with the gas space of the evaporator 3|, at a higherelevation. Through a pipe 62 connected to the liquid space of theevaporator 3|, and forming a heat exchanger with the pipe 36, absorptionliquid ethylene dichloride in paramn oil) flows from the evaporator llinto the abovementioned rising pipe 36. The gaseous working medumflowing from the pipe 26 into the pipe 33 rises with this solution intothe re-absorber 26. Here it is absorbed by the solution and gives upheat to the surroundings. The ethylene dichloride vapor evaporated fromthe absorption solution in the evaporator ll, for which process heat istaken from the surroundings, passes through a pipe 36 into the absorber26, where it enriches the weak solution entering through the pipe 26.The enriched solution flows through a pipe 21, which'forms aheat-exchanger with the pipe 26, to the generator 2|. The gas space ofthe absorber 26 is provided with an air discharging device 34 by themeans of which gaseous parts, which may have penetrated into theabsorber and are not absorbable, may be removed from the refrigeratingmachine.

In the refrigerating machine last described, two completely separatecirculations of absorption liquid take place. In both systems (generator2 I gas separation chamber 24, absorber 26 on the one hand, andre-absorber 29, evaporator 3| on the other hand), the circulation of theliquid is maintained by the absorption liquid being lifted by thegaseous ethylene dichloride developed in the generator 2i. Thecirculation'of the liquid between the generator and the absorber,situated at a higher level, is facilitated by the fact that the strongsolution containing much ethylene dichloride and therefore having ahigher specific where the gas and gravity moves mostly downwards in thepipe 21, whereas a specifically lighter solution rises inthe pipe 23.

I claim as my invention:-

1. In a continuous absorption refrigerating system using ethylenedichloride as a refrigerant and parafiln oil as an absorbent, anabsorber, a generator located below said absorber, conduits connectingthe generator and the absorber for circulating the paraflln oil betweenand through the same, means for causing the ethylene dichloride toevaporate from a liquid to produce a cooling eflect, means for conveyingthe ethylene dichloride vapor into the absorber to cause it tobeabsorbed by the paraflln oil therein and be conveyed to the generator,means for appiyi'ng heat to the generator to expel the ethylenedichloride from the paraffin oil and means for condensing the expelledethylene dichloride and conducting it into the evaporating means, thearrangement being such that as the ethylene dichloride is supplied tothe paramn oil in the absorber, conducted downwardly from the absorberto the generator in solution in the parafiln oil and expelled from theparaffin oil in the generator the circulation of the paraflin oil isfavorably influenced due to the fact that the density of the solution ofethylene dichloride and paraflln oil is greater than the density of theparaflln oil per se.

2. A continuous absorption refrigerating system including an absorber, agenerator located below the absorber, conduit means for conveying anabsorption liquid downwardly from the absorber to the generator, conduitmeans for conveying the absorption liquid from the generator back to theabsorber, means for adding a refrigerant to the absorption liquid in theabsorber and for removing the refrigerant from-the absorption liquid inthe generator, said refrigerant having a greater'speciflc gravity thanthe absorption liquid whereby the density of the liquid is increased inthe absorber and decreased in the generator due to the addition andremoval of refrigerant to foster circulation of the absorption liquidunder the influence of gravity.

3. A continuous absorption refrigerating system including an absorber, agenerator, a conduit for conveying a liquid from the absorber to thegenerator, a conduit for conveying a liquid from the generator to theabsorber and an arrangement causing circulation of said liquid'throughsaid conduits including means for adding a fluid to the liquid in anabsorber and removing the fluid from the liquid in the generator, thefluid having a greater specific gravity than the liquid therebyincreasing the density of the liquid in the absorber and decreasing thedensity of the liquid in the generator whereby circulation may befostered by the action of gravity on the portions of the liquid ofdifferent density.

4. The method of causing the circulation of an absorption liquid in acircuit between the absorber and the generator of a continuous absorption refrigerating system which includes the steps of causing the liquidto absorb a gas, in the absorber to thereby increase the density of theabsorption liquid and expelling, the absorbed gas in the generator todecrease the density of the absorption liquid, and fostering circulationof the liquid under the influence of gravity action on the portions ofthe absorption liquid of diflerent density.

EDMUND ALTENKIR-CH.

